Statistical analysis of ground water distribution in Alessandria Province (Piedmont—Italy)

29 chemical and physical–chemical features of water samples from 44 wells were analysed by multivariate statistical tools to provide the characterisation of the ground water distribution of the North–West area of Alessandria province (Piedmont—Italy). The 29 parameters determined include: temperature, pH, conductivity, dissolved oxygen, suspended solids, COD, total hardness, total phenols, fats and oils, non-ionic surfactants, chlorinated solvents, total chromium, P2O5 and several cations and anions (NO3−, NH4+, Ca2+, Na+, K+, Mg2+, Cl−, SO42− , SO32− , S2− , Fe3+ , Mn2+ , Zn2+, Al3+, Ni2+, Pb2+). The sampling took place during the spring and summer 2001. The use of Principal Component Analysis together with refined mapping tools (kriging methods) provided a description of the area investigated with respect to the characteristics of the subterranean waters. A significant difference in water composition has been highlighted between small villages (with a probable human polluting effect) and zones far from the built-up areas. Cluster analysis was also performed in order to evaluate the different wells similarity and confirmed the results obtained by Principal Component Analysis.